Personally i think the Milltek exhausts are a little tame. Although the new race plus one (76mm system) does sound better on the vid Iain showed me. Not heard it in real life though.
The 90mm race system he has with the downpipes on his demo sounds mean though!
Having listened to a few different exhausts i think i've made my mind up of the 90mm Titan system from GTC. Just need to decide if it needs the downpipes as well